I got a 67 Mustang GTA 390 and it has very poor performance for being 390 cubic inches. It does not smoke or have much blowby but I want much more performance. I bought a 69 429 with C/6 late last year from a very strong running Mercury and was planning on putting that in my Mustang but I just came across a 428 crank cut .010/.010 and fresh .030 block for $500 and I'm now thinking of using that instead. Can I get the 428 to run low 12s or high 11s easily or should I just use the 69 429? I have a friend that has a machine shop and ports heads and owes me a good port job from a deal made last year. I see I can get forged TRW flat top pistons for $303 from summit for the 429 but I can't find any flat top pistons for the 428. I want between 11-12 to 1 compression and want some where around 6000-6500 rpm shift points using the 3000 stall Hughes C-6 converter I already have. Whichever engine I use, I will get headers so that isn't an issue and I have engine mounts for the 429 already too. Which would be better for performance and longevity? I want the engine to last and need to outrun my GM buddies or should I say "unfortunates". I am a mechanic but I don't know much about building a high hp Ford engine, just stock. Thank you and this forum is great. soo much information and knowledgable people here I know I can reach my goal with your help.